Mobile scaffold



June 23, 1970 R. M. KUPKE ETA!- 3,516,512

' MOBILE SCAFFOLD Filed March 6, 1968 3 Sheets-Sheet 1 INVENTORS RUDOLFM. KUPKE KARL-HEINZ LADWIG PETER LADWIG C. A. MANFRED MORTENSEN H. HARRYHANDSHACK ATTORNEY June 23,1970 R. M. KUPKE ETI'AL MOBILE SCAFFOLD 3Shgets-Sheet 3 Filed March 6, 1968 INVENTORS m mwwm Mmm mmm FIT LEED 0 Pw F Rm N M A. C.

' HARRY ELKIDSFA-Ch \Ukf ATTORNEY June 23, 1970 R. M. KUPKE ETAL MOBILESCAFFOLD Filed March a, 1968 3 Sheets-Sheet 5 United States Patent US.Cl. 18216 25 Claims ABSTRACT OF THE DISCLOSURE A mobile scaffold whereina wheel-mounted carriage supports a multi-section upright tower whichguides a vertically movable rectangular work platform provided withhingedly mounted auxiliary platforms. The tower is ec centric withreference to the carriage and one longer side of the platform has arecess for the tower. The drive for the platform comprises a row ofteeth provided on one standard of the tower, a wheel which carries anannulus of rollers engaging with successive teeth during movement of theplatform and two reversible electric motors mounted on the platform torotate the wheel by way of self-locking transmissions. Stabilizing armsare detachably connected with the carriage so as to be movable betweenextended and retracted positions in response to detachment from,inversion by 180 degrees, and renewed attachment to the carriage.

Bridges can be employed to connect the platform with the platform orplatforms of one or more adjoining scaffolds. Such bridges are pivotablewith reference to the platform so that they can be moved to or fromhorizontal positions.

BACKGROUND OF THE INVENTION The present invention relates to scaffoldsin general, and more particularly to improvements in mobile scaffolds ofthe type wherein a work platform is movable up and down along a tower ormast.

Presently known scaffolds of the just outlined character normallycomprise a work platform which fully surrounds the tower from all sidesand wherein the height of the tower can be changed by adding or removingsections at its upper end. The drive for the platform comprises a rackon the tower and a pinion mounted on the platform and meshing with therack. A serious drawback of such scaffolds is that the parts of thedrive undergo excessive wear, that their operation is affected byimpurities in the surrounding atmosphere, and that they require frequentand extensive maintenance. Furthermore, and since the platform surroundsthe tower from all sides, the latter cannot be readily attached to abuilding front or the like in order to enhance the stability of thescaffold when the tower is very tall. Still further, such scaffoldscannot be moved sufficiently close to buildings or like edifices whichare provided with wings, balconies or other protuberances. Additionalproblems arise when the drive for the platform employs an electric motorbecause the conductors serving to supply electrical energy to a motorwhich is mounted on and moves with the platform must receive current byway of brushes, slip rings and like parts which undergo considerablewear. Furthermore, conventional scaffolds are not sufficiently versatilein that their personnelor work-supporting area cannot be enlarged orreduced to the extent necessary to insure economical operation inconstruction, building or bridge maintenance, wire laying, painting,plastering, cleaning and/ or like work. As a rule, the area of the workplatform is changed by resorting to extensible 0r retractible panelswhich are connected with counterweights serving to stabilize thescaffold when ice the panels are moved to extended positions. Thecounterweights add to the bulk of the scaffold and limit the maximumheight of the tower as well as the capacity of the work platform toaccommodate personnel and/or other loads.

SUMMARY OF THE INVENTION It is an object of our invention to provide amobile scaffold which can be hitched to trucks, trailers or like primemovers for transport to and from the locale of use, whose dimensions aresuch that it can be transported on public roads, and whose height can bereadily and rapidly altered by a small number of workmen.

Another object of the invention is to provide a mobile scaffold whichcan be used indoors or outdoors, which can be readily and rapidlyconverted to accommodate larger or smaller groups of workmen and/orsmaller or heavier and bulkier loads, and which can be transported alongor in the interior of buildings or other edifices by or withoutresorting to a prime mover and without necessitating even partialdismantling for transport over relatively short distances.

A further object of the invention is to provide a mobile scaffold whichcan be assembled with one or more similar scaffolds to form therewith achain of scaffolds adapted to extend along one or more sides of largebuildings or groups of buildings, around a chimney or mast, as well asinto recesses between the wings of buildings or into similarhard-to-reach areas.

An additional object of the invention is to provide a scaffold which canbe used in all types of climates, in snow, sleet, rain, on icy roads orgrounds, in mud or on grounds covered with fragments of constructionmaterial, and which can be moved sufficiently close to an edifice or thelike to enable the workmen to perform their tasks without leaving theplatform or platforms of the scaffold.

A concomitant object of the invention is to provide a rugged scaffoldwhich requires little maintenance, which comprises a relatively smallnumber of simple parts, which is provided with simple, compact andreliable means for moving workmen and materials to a desired level, andwhich is sufficiently safe to meet the regulations of authorities whichdetermine the standards for construction, building maintenance, repair,bridge maintenance, wire laying and like equipment.

Still another object of the invention is to provide a mobile scaffoldwhich is provided with stabilizing devices capable of being moved to andfrom retracted positions in which they cannot interfere withtransportation of the scaffold on narrow roads, and which is alsoprovided with a novel system of means for supplying electrical energy toits motors and/ or other current-consuming units.

An ancillary object of the invention is'to provide a mobile scaffoldwhich, in addition to serving as a highly versatile piece of equipmentin construction, building maintenance, lighting installation or repair,wire laying, painting, plastering, cleaning and/or like work, can beused to facilitate the work of personnel in changing its overall height.

A further object of the invention is to provide a mobile scaffold whosemanipulation is very simple and which is provided with a novel drivesystem for moving the workmen and/or materials to a desired level abovethe ground.

An additional object of the invention is to provide a scaffold whoseheight can exceed or at least equals that of presently known scaffordsand wherein the area which be coupled to a tractor or the like, andseveral adjustably mounted stabilizing arms provided with groundcontacting legs and/or wheeled trucks, an upright tower which iseccentrically mounted on the carriage and comprises a stack ofsuperimposed sections consisting of three or more parallel standards oftubular steel stock or the like and stiffening braces connecting thestandards, a work platform having an eccentrically located recess forand being movable up and down along the tower whereby the platformpartially surrounds the tower cooperating guide means provided on thetower and on the platform to guide the latter during movement toward oraway from the carriage and preferably including clusters of rollsmounted on the platform and rolling along two or more standards of thetower, and drive means for moving the platform with reference to thetower. Such drive means preferably comprises a row of teeth provided onone of the standards, a wheel rotatably mounted on the platform andhaving an annulus of rollers engaging with successive teeth when theplatform is in motion, and a pair of electric motors mounted on theplatform and arranged to drive the wheel by way of self-lockingtransmissions. Such motors may receive current through a cable the upperend of which is mounted on the platform and the lower portion of whichis convoluted on a cable drum fixed to the carriage. The cable is beingcollected on or withdrawn from the drum in automatic response downwardor upward movement of the platform.

The novel features which are considered as characteristic of theinvention are set forth in particular in the appended claims. Theimproved scaffold itself, however, both as to its construction and itsmode of operation, together with additional features and advantagesthereof, will be best understood upon perusal of the following detaileddescription of certain specific embodiments with reference to theaccompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a fragmentary sideelevational view of a mobile scaffold which embodies one form of ourinvention;

FIG. 2 is a top plan view of the scaffold with certain parts brokenaway;

FIG. 3 is a side elevational view of a bridge which connects twoscaffolds of the type shown in FIGS. 1 and 2; and

FIG. 4 is a fragmentary top plan view of a modified mobile scaffold.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring first to FIGS. 1 and2, there is shown a mobile scaffold which comprises an underframe orcarriage 1 having two road wheels 2 with inflated tires and a verticallyadjustable hitch 3 by means of which the scaffold can be attached to atruck, tractor or other suitable prime mover. The carriage 1 supportsthe lowermost section 9 of a multi-section tower or mast 4 which is oftriangular cross-sectional outline and extends into a triangular recess10b provided in one longitudinal side 10a of a main work platform 10,namely, in that side which is adjacent to the front of a building orother edifice which is being erected or repaired by workmen employingour scaffold. As shown in FIG. 1, the tower 4 is installed eccentricallymidway or nearly midway between the longitudinal ends of the carriage 1and one of its three sides is parallel to and flush with or closelyadjacent to the side 1011. Each section 9 of the tower 4 comprises threevertical uprights or standards 5', 5, 6 and diagonal stiffening braces 7a few of which are shown in FIG. 2. The sections 9 are coupled to eachother, endto-end, by quick-release couplings 8 of any known design. Themain work platform which is movable up and down along the tower 4 ispreferably employed to transport sections 9 upwardly so that workmenstanding on 4 the platform can manipulate the couplings 8 to assemble atower of desired height.

Each corner portion of the substantially rectangular carriage 1 can beconnected with an elongated stabilizing arm 11 by means of bolts 12 oranalogous fasteners. FIG. 2 shows two of the arms 11 by solid lines intheir normal or extended positions in which they extend laterally andwell beyond the platform 10 (see the two upper arms 11 in FIG. 2). Theother two arms 11 are shown by solid lines in their retracted orconcealed positions 13 in which they extend in substantial parallelismwith the adjacent longer side 10a of the substantially rectangularplatform 10. The extended positions of these two other arms 11 areindicated by phantom lines. In order to move an arm 11 from extendedposition to the retracted position 13, the arm must be detached from thecarriage 1 (removal of bolts 12), inverted about its longitudinal axisby degrees, and reattached to the carriage in retracted position. Thiswill be readily understood by observing the positions of bolts 12 inFIG. 2. All of the arms 11 are moved to extended positions when it isnecessary to assemble a tall tower 4 so as to prevent tilting andeventual over-turning of the scaffold. However, when the work platform10 must be moved close t the front of a building or the like, two of thearms 11 are moved to retracted positions 13 in a manner as shown in FIG.2 so that the tower 4 may be moved close to the front of the buildingand, if necessary, attached thereto at one or more points. In otherwords, when the two lower arms 11 of FIG. 2 are moved to the retractedpositions 13, each section or one or more sections 9 of the tower 4 canbe secured to an edifice which requires repair or other treatment. Thisis possible because the braces 7 between the standards 5 of the tower 4are readily accessible.

The outer end portion of each arm 11 carries a vertical spindle 14 andthe end portions 15 of each spindle constitute female coupling elementswhich can be connected with male coupling elements provided ongroundengaging legs 16. The spindles 14 are externally threaded and meshwith nuts in the outer end portions of the respective arms 11 so thatthey may be moved axially to adjust the inclination and/or height of thecarriage 1. A crank or a like tool (not shown) can be coupled to theupper end portion 15 of each spindle 14 to facilitate its rotation withreference to the arm 11. As shown in FIG. 1, the end portions 15 areprovided with diametral slots 17 which can receive a complementary ribor a like projection on the crank. Each leg 16 can be connected toeither end portion 15 of the respective spindle 14, i.e., these legs canbe applied to the spindles irrespective of whether the arms 11 aremounted in extended or retracted positions. In order to move an arm 11from extended position to retracted position or vice versa, theoperators simply detach the cranks from the upper end portions 15 andthe legs 16 from the lower end portions 15 of the respective spindles 14and thereupon detach the arms 11 from the carriage 1 prior to inversionof arms and reattachment to the corresponding corner portions of thecarriage.

If the ground which supports the scaffold is solid, e.g., if thescaffold is used in a hall or on a paved street for repair of buildingfronts, it is often desirable to roll the scaffold along the building orfrom a building to the next locale for use. Such rolling or transportcan be effected without necessitating and dismantling or shortening ofthe tower 4. To this end, a wheeled truck 18 can be mounted below eachleg 16 and secured thereto by mating male and female threads or by oneor more bolts and nuts or the like. The legs 16 and the trucks 18 arefree to swivel about the axes of the respective spindles 14 so that thescaffold can readily change the direction of its travel. In order toprevent uncontrolled changes in direction during transport, each truck18 preferably comprises two coaxial rolls or Wheels 19a and a thirdcentrally located steering wheel or roll 19 which is offset withreference to the wheels 19a. The wheels 19a are located at the oppositesides of the respective spindle 14.

The work platform 10 comprises a profiled rectangular frame 21 which isreinforced by longitudinally, transversely and/or otherwise extendingstiffening braces 20. The inclined braces 20a shown in FIG. 2 areadjacent to longer side 10a of the platform 10 and define betweenthemselves a substantially triangular recess or passage for the tower 4.The outer ends of the inclined braces 20a are adjacent to two verticallyextending supporting tubes 22 which are sufficiently strong to withstandsubstantial bending, twisting and other stresses. The lower end portionsof the supporting tubes 22 are connected to the opposite corner portionsof the frame 21 by diagonal braces 23. The supporting tubes 22 form partf a guide means for the platform 10 and each thereof carries four pairsor clusters of guide rolls 24, 2'5 rotatable about horizontal axes andarranged to roll along the adjoining standards of the tower 4. Two pairsor clusters of rolls 24, 25 are disposed at each end of each supportingtube 22 and the axis of each roll 24 makes with the axis of theadjoining roll 25 an angle of 12.0 degrees. The axes of the rolls 24 areparallel with the adjacent longer side a of the platform 10 (see FIG.2). The rolls 24 take up the major part of the weight of the platform 10whereas the rolls 25 prevent sidewise movements of the platform. Thearea between the left-hand and righthand rolls 24 is accessible so thatthe braces 7 between the standards 5 can be readily attached to abuilding front or the like for reasons which were explained hereinbefore. Such tying of the tower 4 to the building front is oftendesirable to prevent swaying and/ or to counteract excessive bendingand/or other stresses. The tower 4 can be attached to a building atregular or irregular intervals.

The drive which serves to move the platform 10 up and down along thetower 4 comprises a row of teeth 26 provided on the standard 6 atregular intervals and having top faces of epicycloidal outline. Theteeth 26 cooperate with an annulus of six equidistant rollers 27provided on a driven wheel 28 which is formed or rigid with a peripheralspur gear meshing with-two pinions 30. The wheel 28 is mounted in abearing bracket 29 which is affixed to the underside of thelongitudinally extending central stiffening brace 20 of the frame 21.Each pinion 30 is mounted on the output shaft of one of two self-lockingtransmissions 31 receiving torque from two braked reversible electricmotors 32. The transmissions 31 and motors 32 are mounted at theunderside of the centrally located brace 20 at the opposite sides of thebearing bracket 29. Two such motors and two transmissions are providedfor the sake of safety. The distance between the teeth 26, the diametersof rollers 27, the configuration of top faces on the teeth 26, thediameter of the circle on which the axes of the rollers 27 are locatedand certain other characteristics of the just described drive for theplatform 10 are selected in such a way that the platform can be moved ata constant rate of speed. At least one tooth 26 engages with at leastone roller 27 in each position of the platform 10. The torsional momentexerted by the eccentrically mounted platform 10 upon the guide rolls24, 25 is taken up only in part by the rollers 27 to thus insuremovements of the platform without any wobbling. Since the rollers 27merely roll along the top faces of the teeth 26, these teeth need not belubricated and deposition of dirt or dust on such top faces does notinfluence the operation of the drive. Also, the wear on the parts 26, 27is rather negligible. The feature that the teeth 26 need not belubricated is of particular importance when the scaffold is used atconstruction sites where the air is laden with dust.

The frame 21 of the platform 10 carries four auxiliary platformsincluding two end platforms 33 which are hingedly connected to theshorter sides of the platform 10 and two lateral platforms 34 which arehingedly connected to the longer side 10a and flank the tower 4. The endplatforms 33 are moved from their raised or inoperative positions (seethe left-hand platform 33 in FIG. 1) to the operative positions shown inFIG. 1 in order to form with the main platform 10 an enlarged compositeplatform of greater length. The later platforms 34 can be foldedupwardly above or downwardly below the main platform 10. These lateralplatforms are shown in FIG. 2 in operative positions in which theyextend toward a building or the like and enable the workers to movecloser to the front of the building. When moved to inoperativepositions, the lateral platforms 34 enable the scaffold to bypass wings,balconies and other protuberances on the building or buildings withoutnecessitating movement of the carriage 1 further away from the build ingfront. The lateral platforms 34 are shown as having solid floors ofwooden planks, sheet metal or the like. The floors 35 of the platforms10 and 33 are preferably made of wire mesh, interlaced steel bars or thelike. Guard rails 37 are provided along the other longer side of themain platform 10 and along the shorter sides of each end platform 33.The guard rail 37 of the main platform 10 has a centrally locatedopening 36 which is normally closed by the uppermost rung of a ladder 38which can be suspended on the upper rod of the guard rail. The uppermostrung of the ladder 38 can be suspended on the lowermost part of theguard rail 37 for the main platform 10 or on the frame 21 when a workmanwishes to enter or leave the main platform.

Our scaffold can be coupled with one or more similar scaffords to formtherewith a chain or train of scaffolds which may extend along the frontof a wide building, along the fronts of two or more buildings or in acircle or semicircle around a mast, chimney or another elevatedstructure. FIG. 3 shows, by way of example, a connection between twoscaffolds A and B having main platforms 10 and and end platforms 33,133. The connection includes a bridge 39 provided with guard rails 39aand having a bottom or floor 39b with extensions or bars 41 which canpass through transversely adjustable sockets 40 provided on the endplatforms 33 and 133. Spring-biased or gravity-actuated locking devices43 are pivotally connected to the ends of bars 41 to preventunintentional separation of the bridge 39 from the two scaffolds. Thelocking devices 43 normally engage stops 42 provided at the ends of bars41 to thus prevent withdrawal of bars from the respective sockets 40. Inorder to detach the bridge 39, the workmen must pivot the lockingdevices 43 into recesses 4112 provided therefor in the bars 41 whereuponthe bars can be readily withdrawn from the respective sockets 40. Othertypes of connectors between the bridge 39 and platforms 33, 133 can beused just as well. The sockets 40 are preferably free to swivel relativeto the platforms 33, 133 about vertical, horizontal and otherwiseinclined axes so that the bridge 39 can be installed in horizontal orinclined position. One or more additional bridges can be employed toconnect the scaffold A and/or B with one or more additional scaffolds.As stated before, the bridge 39 can be used with one or more bridges toconnect two or more scaffolds in a circle or semicircle around a tower,mast, chimney or the like or to form an L-shaped, rectangular,triangular or like chain around other types of tall buildings. When thechain comprises two or more scaffolds, the exposed sides of their towers4 (between the standards 5) can be connected to each other byfiexure-resistant braces or like stiffeners, not shown. The length ofrods 41 on the bridge 39 is preferably such that this bridge can connecttwo closely adjacent scaffolds or a pair of scaffolds which are locatedat a relatively large distance from each other. Furthermore, the bridge39 can be used to enable workers to enter a tall building through awindow or to move onto or from balconies or like projections. Thesockets are preferably arranged to permit mounting of the bridge 39 inhorizontal as well as in strongly inclined position, for example, whenthe platform 33 of the scaffold A is located at a level well above orwell below the platform 133 of the scaffold B. The connection betweenthe scaffolds A and B may comprise two or more bridges 39 which can berigidly or articulately coupled to each other.

Referring again to FIGS. 1 and 2, the means for supplying electricalenergy to the motors 32 and, if necessary, to other electricallyoperated equipment on the platform 10, 33 and/or 34 comprises a flexiblecable 44 which extends from the carriage 1 upwardly to the main workplatform 10. The upper end ofthe cable 44 is connected with a box 45which may accommodate switches or other electrical components and iselectrically connected with the motors 32. The lower end portion of thecable 44 is convoluted around the core of a vertical cable drum 46mounted on the carriage 1. The cable passes through an eye 47 providedat the free end of a rotary and vertically movable winding member 48whose purpose is to wind or unwind the cable off the drum work platform10. The upper end of the cable 44 is con- 46 in response to rotationabout the axis of the drum whereby the eye 47 orbits about the drum andmoves up or down, depending on the direction in which the winding memberrotates. The winding member 48 is connected to the upper end of avertical spindle 49 which extends axially through and meshes with thecore of the drum 46. The lower end portion of the spindle 49 is rigidwith a worm wheel 50 which is freely rotatable in one direction but isself-locking in the other direction. The lower end portion of thespindle 49 further carries a reel or spool 51 which carries a supply ofconvoluted cord or rope 52. The diameter of the core of the drum 46 isthe same as that of the core of the reel 51. The rope 52 is trainedaround a pulley 54 which is mounted on the carriage 1 and its free end53 is attached to the main platform 10, for example, to the lower end ofone of the supporting tubes 22. When the spindle 49 rotates withreference to the drum 46, it causes the winding member 48 to rotate andto move up or down whereby the eye 47 insures accurate winding orunwinding of cable 44 off the core of the drum. When the motors 32 aredriven in a sense to move the platform 10 downwardly, the tension in thecord 52 slackens whereby the pulley 54 changes its position under theaction of a suitable spring (not shown) and actuates a switch 55 whichstarts a motor 57 mounted for up and-down movement wtih the spindle 49and having an output shaft provided with a worm 56 which meshes with theworm wheel 50 on the spindle 49. The motor 57 then drives the spindle 49in a sense to cause the winding member 48 to convolute the cable 44 onthe cable drum 46. If the motor 32 cause the platform 10 to moveupwardly, the tension in the cord or rope 52 increases and the pulley 54opens the switch 55 to arrest the motor 57. The rising platform 10rotates the reel 51 by way of the cord 52 and causes the winding member48 to rotate in a sense to unwind the cable 44 from the drum 46. Animportant advantage of the just described means for supplying electricalenergy to the motors 32 is that the cable drum 46 need not .rotate and,therefore, the lower end of the cable 44 need not receive current fromslip rings or like parts which undergo considerable wear. The rate atwhich the spindle 49 rotates the winding member 48 during upward ordownward movement of the platform 10 is such that the cable 44- is notsubjected to excessive tensional stresses but is sufficiently taut toprevent the formation of large unsupported loops. The eye 47 convolutesthe cable 44 in the form of a series of closely adjacent convolutions.

FIG. 4 illustrates a portion of a modified scaflold wherein arectangular or square tower or mast 204 comprises four standardsincluding three standards 205 and a standard 206. Each of the standards205 is engaged by several pairs or clusters of guide rolls 224, 225whose axes are located in horizontal planes and preferably make witheach other an angle of about degrees. The rolls 224 may but need not belocated at the same level as the rolls 225. A portion of the mainplatform is shown at 210. The tower 204 is eccentric with reference tothe platform 210, i.e., the mounting of the platform is similar to thatof the platform 10.

It is clear that the improved scaffold may have a tower of pentagonal orother polygonal outline without departing from the spirit of ourinvention. Also, the carriage 1 may be provided with two or more pairsof road wheels 2 (with solid or inflated tires) or the wheels 2 can bereplaced by endless treads.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can, by applying current knowledge,readily adapt it for various applications without omitting featureswhich fairly constitute essential characteristics of the generic andspecific aspects of our contribution to the art and, therefore, suchadaptations should and are intended to be comprehended within themeaning and range of equivalence of the claims.

What is claimed as new and desired to be protected by Letters Patent isset forth in the appended claims:

1. A scaffold, particularly a mobile scaffold, comprising a groundsupported carriage having a center; an upright tower of polygonalcross-sectional outline eccentrically mounted on said carriage andcomprising a plurality of upright standards and braces connecting saidstandards, one of said standards extending upwardly from said carriagein the region of the center thereof; a work platform having a center insubstantially vertical alignment with the center of said carriage and aneccentrically located recess for and being movable up and down alongsaid tower, the latter being partially surrounded by said platform;cooperating guide means on said platform and said tower to guide saidplatform during movement along said tower, said guide means including atleast two of said standards and clusters of rolls mounted on saidplatform and arranged to travel along said two standards; and drivemeans on said platform for moving said platform along said tower andengaging means provided on said one standard.

2. A scaffold as defined in claim 1, wherein said drive means compriseselectric motor means mounted on said platform and means for supplyingelectrical energy to said motor means, said energy supplying meanscomprising cable means having an upper end portion connected with saidplatform and a lower portion convoluted on a stationary cable drummounted on said carriage, and means for paying out and collecting saidcable on said stationary drum in response to upward and downwardmovement of said platform.

3. A scaffold as defined in claim 2, wherein said drum has a verticalaxis and said last mentioned means comprises a winding member rotatablewith reference to and movable axially of said drum and having means forwinding the cable on or for unwinding the cable from said drum, andmeans for rotating and moving said winding member axially withreferennce to said drum in response to movement of said platform withreference to said tower.

4. A scaffold as defined in claim 3, wherein said last mentioned meanscomprises a threaded spindle meshing with said drum and rigid with saidwinding member, a reel fixed to said spindle, a flexible elementconvoluted on said reel and having an end portion aflixed to saidplatform to rotate said spindle in one direction when said platformmoves upwardly, and second motor means for driving said spindle in theopposite direction in response to downward movement of said platform.

5. A scaffold as defined in claim 4, wherein said second motor meansdrives said spindle by way of a one 9 way worm drive and furthercomprising means for starting said second motor means in response toreduced tension in said flexible element when said platform movesdownwardly.

6. A scaffold, particularly a movable scaffold, comprising a groundsupported carriage; an upright tower eccentrically mounted on saidcarriage and comprising a plurality of upright standards and bracesconnecting said standards to each other; a work platform having aneccentrically located recess for and being movable up and down alongsaid tower, the latter being partially surrounded by said platform;cooperating guide means provided on said platform and said tower toguide said platform during movement toward and away from said carriage;and drive means for moving said platform with reference to said towerand comprising a row of equidistant teeth provided on one of saidstandards, a driven member rotatably supported by said platform andhaving an annulus of rollers engaging with successive teeth on said onestandard in response to rotation of said driven member, and reversiblemotor means for rotating said driven member.

7. A scaffold as defined in claim 6, wherein said platform has anelongated side and said recess is provided in said side, said onestandard being located in said recess remote from said side of saidplatform.

8. A scaffold as defined in claim 6, wherein said teeth have faces ofepicycloidal shape and said rollers are arranged to engage with and toroll along said faces when the platform is moved with reference to saidtower.

9. A scaffold as defined in claim 8, wherein said faces are the topfaces of said teeth and wherein at least one of said rollers engageswith one of said teeth in each position of said platform.

10. A scaffold as defined in claim 6, wherein said driven membercomprises a gear and said drive means further comprises a plurality ofpinions meshing with said gear and receiving torque from said motormeans.

11. A scaffold as defined in claim 10, wherein said motor meanscomprises a plurality of motors, one for each of said pinions, andself-locking transmission means interposed between each of said motorsand the respective pinion.

12. A scaffold as defined in claim 11, wherein said platform comprises areinforced frame and wherein said motors and said transmission means aremounted at the underside of said frame.

13. A scaffold, particularly a movable scaffold, comprising a groundsupported carriage; an upright tower eccentrically mounted on saidcarriage and comprising a plurality of upright standards and bracesconnecting said standard to each other; a work platform having anelongated side and an eccentrically located recess extending inwardlyfrom said elongated side, said tower extending through said recess andtwo of said standards being adjacent said elongated side of saidplatform and the latter being movable up and down along said tower;cooperating guide means provided on said platform and said tower toguide said platform during movement along said tower, said guide meanscomprising a pair of elongated supporting members provided on saidplatform and each adjacent to one of said two standards, and clusters ofguide rolls provided on said supporting members and arranged to rollalong the respective standards; and drive means for moving said platformwith reference to said tower.

14. A scaffold as defined in claim 13, wherein said tower is ofrectangular outline and comprises four standards connected by saidbraces, said guide means comprising further a third upright supportingmember on said platform adjacent to a third of said standards and acluster of guide rolls being also provided on said third supportingmember, each of said clusters comprising a pair of rolls rotatable aboutsubstantially horizontal axes making an angle of approximately 90degrees.

15. A scaffold as defined in claim 13, wherein said supporting membersextend downwardly from said platform and further comprising stiffeningelements connecting the lower end portions of said supporting memberswith the frame of said platform.

16. A scaffold as defined in claim 15, wherein said tower is oftriangular outline and comprises three standards, each of said clusterscomprising a pair of rolls rotatable about axes located in substantiallyhorizontal planes and making an obtuse angle with each other.

17. A scaffold, particularly a mobile scaffold, comprising a groundsupported carriage; an upright tower eccentrically mounted on saidcarriage and comprising a plurality of superimposed sections detachablysecured to each other end-to-end; a work platform having aneccentrically located recess for and being movable up and down alongsaid tower, the latter being partially surrounded by said platform;bridge means; coupling means for detachably connecting said bridge meansto said platform and comprising sockets adjustably and turnably mountedon said platform and extensions provided on said bridge means andreceivable in said sockets; cooperating guide means provided on saidplatform and said tower to guide the platform during movement toward andaway from said carriage; and drive means for moving said platform withreference to said tower.

18. A scaffold as defined in claim 17, further comprising locking meansfor releasably holding said extensions in the respective sockets.

19. A scaffold as defined in claim 17, wherein said coupling means isarranged to permit movements of said bridge means to and from ahorizontal position with reference to said platform.

20. A scaffold, particularly a mobile scaffold, comprising a groundsupported carriage having a center and a plurality of corner portions; aplurality of elongated stabilizing arms each fixedly connectable to saidcorner portions of said platform in an extended and in a retractedposition in which it respectively projects laterally from and is-nearerto said carriage; an upright tower eccentrically mounted on saidcarriage; a work platform having a center in substantially verticalalignment with the center of said carriage and being movable up and downalong said eccentrically mounted tower, the latter being partiallysurrounded by said platform; cooperating guide means provided on saidplatform and said tower to guide the platform during movement toward andaway from said carriage; and drive means for moving said platform withreference to said tower.

21. A scaffold as defined in claim 20, wherein said stabilizing arms aredetachable from said carriage and are connectable with said carriage infirst positions corresponding to said extended positions and secondpositions corresponding to said retracted positions, each of said armsbeing inverted by approximately degrees upon detachment from saidcarriage in one of said first and second positions and prior to placingit into the other of said first and second positions.

22. A scaffold as defined in claim 20, wherein each of said stabilizingarms has an end portion remote from said carriage, an upright spindlerotatably mounted in the end portion of each of said arms, and aground-contacting le-g detachably affixed to the lower end of eachspindle.

23. A scaffold as defined in claim 22, wherein each of said spindlesmeshes with the respective end portion and comprises coupling means atits upper end to facilitate connection with a device which causes thespindle to rotate and to change its axial position with reference to therespective end portion.

24. A scaffold as defined in claim 22, further comprising a wheeledtruck detachably affixed to and located below each of said legs.

25. A scaffold as defined in claim 24, wherein each of said truckscomprises a pair of coaxial wheels mounted at the opposite sides of therespective spindle and a steering 1 1 12 7 Wheel located midway betweenand offset with reference 2,978,062 3/1961 Di Camillo- 182.63. to saidpair of wheels. 3,016,989 1/1962 vLindmark 18263 I d 3,318,414 5/1967Meek 182146 References FOREIGN PATENTS UNITED STATES PATENTS 5 1,255,5621/1961 France. 2,196,511 3/1940 Wagner 182-625 2,402,579 6/1946 Ross18263 REINALDO P. MACHADO, Primary Examiner 2,787,278 4/1957 Mitchell1322 2,857,994 10/1958 Sheard 182178 US. Cl. X.R. 2,957,592 10/1960Thacker. 10 182-63, 141, 131

